A. Field of the Invention
The present invention relates to methods and apparatus for chemical analysis and more particularly to deployable chemical air sampling systems.
B. Description of the Related Art
Current techniques for chemical air sampling typically use zeolites or metal organic frameworks (MOFs). Zeolites and MOFs derive pore size from their structure, and pore size is “tuned” in fixed size steps. Changing pore size requires a compositional change which is achieved by a chemical change of the linking unit, so that a change in pore size is tied inextricably to the chemical interactivity of pore lining, i.e., a specific chemical lining is linked to given pore size regime. Because of this, it is impossible, for example, to create MOFs with 1 nm and 10 nm pore sizes which have the exact same chemical lining.
In order to selectively sample a wide variety of chemical analytes that differ in size, shape, hydrophilicity, etc, techniques have been employed in which a mixture of adsorbents is used. However, heterogeneous mixtures introduce challenging desorption conditions due to the unique behavior of each component.
The need for environmental monitoring of toxic gases has increased dramatically in recent years for defense, homeland security, and industrial applications. The need exists for a deployable chemical air sampling system in which pore size is not linked to chemical interactivity of the pore lining. The system should be versatile, rapid, and yet low cost. The present invention is directed to meeting this need.